1. Field of the Invention
The present invention relates to a lamp mounting structure. More particularly to a lamp mounting structure capable of aligning the optical axis of a lamp correctly while preventing a lamp from being damaged even when it is overheated. Thereby, the invention enhances the stability in the operation of the lamp and improve convenience in association with the use of the lamp. In particular, the present invention can be effectively employed to the cases in which the alignment of the optical axis of a lamp is important, such as the lamp mounting structures of projectors.
2. Background of the Related Art
Generally, a display device using a projection system includes a projector for projecting the light retaining an image signal, and a screen for reflecting the light projected from the projector, thereby displaying an image. The projector mainly includes a lamp for performing a light emitting function, a plurality of dichroic mirrors for reflecting or transmitting the light (white light) emitted from the lamp selectively, a liquid crystal panel for receiving the light beams separated from the light by the dichroic mirrors, thereby forming an image while controlling the amount of the light incident on each pixel thereof, and projection lens for projecting the image formed by the liquid crystal panel while enlarging the image.
The lamp is an essential component of the projector since it determines the basic performance of the projector such as controlling the brightness and color of the image projected onto the screen. FIGS. 1 and 2 illustrate an embodiment of a conventional lamp. Referring to FIGS. 1 and 2, the lamp 10 includes a funnel 12 serving as a mirror, a frame 14 attached to the front end of the funnel 12, an iron core 16 arranged at the rear portion of the funnel 12, a neck 18 adapted to partially surround the iron core 16, and a connecting bolt 19 protruded from the iron core 16. Metal material such as iron could be used to make the iron core 16. The iron core 16 is mounted on the neck 18 by a gypsum material interposed therebetween.
The brightness and the color of the image displayed by the projector vary greatly, depending on the direction of the light emitted from the lamp 10. Accordingly, it is necessary to firmly maintain the mounted state of the lamp 10. To this end, the lamp 10 is firmly and accurately mounted by a lamp holder 20 in order to prevent the optical axis of the lamp 10 from being miss-aligned in lateral, vertical and logitudina directions, the directions of X, Y, and Z axis in FIG. 1, respectively.
The lamp holder 20, which serves as a mounting structure of the lamp 10, has a bottom plate 201, a front plate 202, and a pair of side plates 203. The guide plates 22 are placed at both sides of the front plate 202 to fasten the right and the left sides of the frame 14 to the lamp holder 20. Vertically-extending guide plates 22 are provided at both sides of the rear surface of the front plate 202. The guide plates 22 serves to the frame 14 of the lamp 10, thereby holding the lamp 10 in the longitudinal, z-axid, and lateral, x-axis, directions. The lamp holder 20 also has a strip-shaped holding plate 30 mounted between the side plates 203 to hold the lamp 10 in the vertical, y-axis, direction. Both ends of the holding plate 30 are fitted in slots 203, which are formed at the side plates 203, respectively.
In the conventional lamp mounting structure having the above mentioned configuration, movements of the lamp 10 in lateral, x-axis directions are restricted by the guide plates of the lamp holder 20, and movements of the lamp 10 in vertical, y-axis, directions are restricted by the holding plate 30. Also, movements of the lamp 10 in longitudinal, z-axis, directions are restricted by the front plate 202 of the lamp holder 20 and stoppers that are provided at the lower end of the guide plates 22. Thus, the movements of the lamp 10 are restricted to prevent the optical axis of the lamp 10 from miss-alignments in any direction.
Meanwhile, heat generated as a result of a high temperature, for example, about 300xc2x0 C. or above, at the lamp 10 isdue to the operations of the lamp 10. This heat serves to over-heat the lamp 10, thereby causing the funnel 12 and the frame 14 to expand. When the funnel 12 and frame 14 expand, an excessive pressure is applied to the funnel 12 by the lamp holder 20. Since the lamp 10 is placed in between the guide plates 22 of the lamp holder 20, the expansion may result in a crack, either at the funnel 12 or the neck 18.
If the width L2, the defined space between the guide plates 22, increases in order to prevent the lamp 10 from being damaged due to a thermal expansion as described above, then the lamp 10 may move laterally resulting in a miss-alignment of the optical axis a normal state. Also, there may be a degraded uniformity of the image displayed on the screen. In particular, the miss-alignment of the optical axis causes the displayed image on the screen to undesirably exhibit undersirable excessive yellow color at the periphery thereof.
Therefore, the present invention has been made in view of the above mentioned problems. An object of the invention is to provide a lamp mounting structure for a projector which is capable of maintaining a desired alignment of the optical axis of a lamp included in the projector while allowing the lamp to move freely to an certian extent. Thereby the invention will be able to prevent the lamp from being cracked due to an expansion caused by an excessive heat, thus achieving an improved stability in the operation of the lamp.
In accordance with the present invention, the object is accomplished by providing a mounting structure for a lamp comprising: a lamp having a funnel, a frame attached to a front end of the funnel, and a connecting bolt provided at a rear portion of the funnel; a lamp holder, which is adapted to hold the lamp therein while maintaining a desired lateral gap at each side of the frame of the lamp, has a bottom plate, a front plate and a pair of side plates; and a guide that elastically supports the lamp in position comprises hinges formed at the opposite ends of the guide and mounted on the bottom plate of the lamp holder in a manner that allows the hinges to rotate, an engagement member arranged at an intermediate portion of the guide and placed at an upper end of the front plate of the lamp holder and a contact member that is formed at the opposite sides of the engagement member and comes in contact with the lamp.
The lamp mounting structure according to the present invention allows the lamp to be enlarged and shifted to a certain extent with the structure of the lamp holder. Therefore, this structure prevents either the funnel or the neck of the lamp from being cracked even when the lamp is heated. Accordingly, it is possible to lengthen the life of the product to which the lamp mounting structure is employed. In addition, the lamp mounting structure elastically holds the lamp using the structure of the tension guide. Accordingly, when the optical axis of the lamp is miss-aligned due to a shift of the lamp, this miss-alignment is immediately corrected. Thus, there is an advantage in that an improved stability in the operation of the product, for example, a projector, is achieved.